Method for forming an underground wall comprising a plurality of columns in the earth and soil formation

ABSTRACT

A method for forming an underground wall comprising a plurality of columns in the earth and soil formation in which a vertically and rotationally movable hollow shaft having integral digging means and nozzle means is advanced into the earth and soil formation to a predetermined depth as it is rotated so as to form a cavity in the formation having a predetermined depth and upon the formation of the cavity, the shaft is retracted from the cavity as it is rotated and simultaneously, solidification and densification liquid agent is radially pumped through the nozzle means into the earth and soil formation so as to mix the liquid agent with the earth and soil to form a column along the shaft.

United States Patent n 1 Nakanishi Apr. 2, 1974 METHOD FOR FORMING AN UNDERGROUND WALL COMPRISING A PLURALITY OF COLUMNS IN THE EARTH AND SOIL FORMATION [76] Inventor: Wataru Nakanishi, Room 301 lkedayama Mansion ll-l Gotanada 4-chomc, Shinagawa-ku, Tokyo, Japan [22] Filed: Nov. 24, 1971 [2]] Appl. No.: 201,812

[30] Foreign Application Priority Data Nov. 30, 1970 Japan 45-104831 [52] US. Cl 61/35, 61/50, 6l/53.64 [51] Int. Cl EOZd 7/00, E02d 29/00 [58] Field of Search 61/35, 36 R, 63, 53.64,

[56] References Cited UNITED STATES PATENTS 3,391,544 7/1968 Daczko 6l/53.64 3,326,003 6/1967 Marconi 61/50 3,270,5ll 9/1966 Colle 6l/53,64 2,79l,886 5/1957 Vcdcr 6l/53.52

Primary ExaminerMcrvin Stein Assistant Examiner-Alex Grosz Attorney, Agent, or Firm-Hammond & Littcll [57] ABSTRACT A method for forming an underground wall comprising a plurality of columns in the earth and soil formation in which a vertically and rotationally movable hollow shaft having integral digging means and nozzle means is advanced into the earth and soil formation to a predetermined depth as it is rotated so as to form a cavity in the formation having a predetermined depthand upon the formation of the cavity, the shaft is re tracted from the cavity as it is rotated and simultaneously, solidification and densification liquid agent is radially pumped through the nozzle means-into the earth and soil formation so as to mix the liquid agent with the earth and soil to form a column along the shaft.

3 Claims, ll Drawing Figures PATENIEDAPR 2W4 3.800.544

' sum 1 or a v INVENTOR W A TARU 'NAKANISHI PATENIED APR 2 I974 SHEET 2 [IF 3 I INVENTOR WATARU NAKANISHI PATENIEDAPR 2 I874 sum 3 or 3 INVENTOR WATARU NA KANl6Hr BY t I W TTORN Y BACKGROUND OF THE INVENTION This invention relates to the solidification, densification and strengthening of the soil and earth formation and more particularly, to a method of forming an underground wall comprising a plurality of successive columns in the earth and soil formation by forming successive columns in the earth and soil formation by means of forcing a solidification and densification liquid agent in the earth and soil formation whereby in the construction of the foundation of a building and the like structure, an underground passage or a tunnel in the earth and soil formation, ground leakage of water, gushing out of water and/or landslide can be effectively prevented resulting in smooth and safe construction work.

There have been proposed a number of methods of forming an underground wall in the earth and soil formation of the above-mentioned nature which are pri- Y marily directed to preventing ground leakage of water through walls of the embankment of a water reservoir, dam or river and also to preventing gushing of water into the underground construction site by solidifying and densifying the earth and soil formation. 7

Another prior art method of solidification, densification and strengthening of the earth and soilformation is directing to protecting an underground structure such as a bridge girder or foundation.

ln the formation of an underground wall in the earth and. soil formation for the purpose of prevention of ground leakage of water and/or gushing out of water, it has been the general procedure that a vertical cavity is first drilled by specific drilling means in the earth and soil formation where ground leakage of water and/or gushing of water are present and then an earth and soil solidification and densification liquid agent is forced into the cavity or steel sheet piles are driven into the cavity. Alternatively, a vertical cavity is previously drilled'in such earth formation and thereafter, cement grout is poured into the cavity so that ground leakage of water, gushing of water in and/or collapse of the earth and soil formation can be prevented.

And in the formation of the foundation of an underground structure in a soft region of the earth and soil formation, such soft region has been solidified or strengthened by digging the earth andsoil material out of such region to leave a cavity there and then pouring concrete into the cavity using specific side wall forming frames or by. digginga rather large diameter cavity in the soft earth and soil formation region and successively forming columns with an earth solidification liquid agent to provide a solidification underground wall.

However, in the formation of ground water leakage prevention walls or earth and soil solidification walls by any of the conventional methods referred to above, it was necessary to perform various inconvenient and costly'operations such as driving of steel sheet piles, formation of side piles and/or provision of holes for pouring of an earth and soil solidification liquid agent.

Furthermore. the prior art methods of the formation of underground walls of such nature required a low of manual efforts and could not be efficiently performed in a short period of time.

SUMMARY OF THE INVENTION Thus, one object of the present invention is to provide an improved method of the formation of an under-' ground wall comprising a plurality of successive columns.

A further objectof the present invention is to provide an automatic method for the formation of an underground wallcomprising a plurality of successive columns without the necessity for separate digging means for forming a cavity in the earth and soil formation in which a hollow digging shaft provided with a plurality of earth solidification liquid agent openings or nozzle means in the peripheral wall is forced into the earth and soil formation at a selected area as it is rotated to a predetermined depth and when the shaft has reached the predetermined depth, the shaft is pulled up as it is rotated and at the same time an earth solidification and and densification liquid agent is pumped through the openings in the shaft into the earth and soil formation to form an earth solidification column and after the completion of the operation in the selected area, the same procedure is repeated in another area of the earth and soil formation adjacent to the first area. The procedure is repeated in successive areas in the earth and soil formation until an underground wall comprising a predetermined number of successive columns is formed.

Another object of the present invention is to provide an automatic method of the formation of an underground wall comprising a plurality of successive columns in the earth and soill formation by pumping an earth solidification and densification liquid agent into the earth and soil formation so as to mix the liquid agent with the earth and soil. I

Another object of the present invention is to provide a method for the formation of an underground wall comprising a plurality of successive columns in the earth and soil formation without the necessity for specific separate digging means so as to form a cavity in the earth and soil formation in which an earth solidification and densification liquid agent is directly pumped to mix the liquid agent with the earth and soil whereby the underground wall can be efficiently and simply formed in a short period of time.

A further object of the present invention is to provide a method for the formation of an underground wall comprising a plurality of successive columns which concurrently serves as a ground leakage of water prevention and earth formation solidification means in which a vertically and rotationally movable hollow shaft provided with a plurality of integral earth solidification and densification liquid agent openings or nozzle means in the peripheral wall and integral digging means at the lower end is vertically driven into the earth and soil formation as it is rotated to a predetermined depth and when the shaft has reached the predetermined depth, the shaft is pulled up and at the same time an earth solidification and densification liquid agent is pumped through the shaft openings into the earth and soil formation so as to mix the liquid agent with the earth.

present invention, the hollow shaft provided with a plurality of integral earth solidification and densification liquid agent openings or nozzle means and integral dig- For attaining the above purposes, according to the ging means is driven into the earth and soil formation to a predetermined depth as is rotated. The digging means are integrally provided at the lower end of the shaft extending in parallel to the axis of the shaft and the openings or nozzle means are provided in the peripheral wall of the shaft at right angles to the axis of the shaft. The fluid or earth and soil liquid solidification and densification agent is pumped by a pneumatic pump disposed on the ground the earth and soil formation underneath which is to be solidified and densified through the nozzle means radially into the earth and soil formation along the shaft as the shaft is pulled up while rotating.

In this way, as the earth and soil solidification and densification liquid agent is continuously pumped along the vertically and rotatably moving shaft, an underground strengthening wall which serves as ground leakage of water prevention and earth solidification or densification means can be continuously and simply formed in the earth and soil formation.

The above and other objects and'attendant advantages of the present invention will be more clearly apparent to those skilled in the art from a reading of the following detailed description of the invention in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 through inclusive are schematic view showing the underground wall formation method of the present invention in various stages in which:

FIG. 1 is a schematic view in partial section showing the method at the outset or initial stage;

FIG. 2 is a schematic view in partial section showing the method at a further progresed stage wherein the lower end of the hollow shaft is positioned at the bottom of a cavity of a predetermined depth in the earth and soil formation;

FIG. 3 is a schematic view showing the manner in which an earth and soil solidification or densification liquid agent is pumped through nozzle means provided in the shaft into the earth and soil formation;

FIG. 4 is a schematic view in partial section showing the manner in which a column which constitutes of a part of a desired underground wall in the earth and soil formation is formed as the shaft is retracted or pulled upwardly from the cavity while being rotated;

FIG. 5 is a schematic view in partial section showing a complete column which extends from the ground to the predetermined depth in the earth and soil formation;

FIG. 6 is a schematic perspective view of an assembly of complete underground walls each comprising a plurality of successive columns;

FIG. 7 is a schematic perspective view showing a modified form of underground wall formed by the present invention in which a transverse opening is provided in an intermediate height of the wall;

FIG. 7A is a schematic perspective view showing a further modified form of underground wall formed by the present invention which comprises a plurality of inclined underground walls in two rows with the alternate columns in one row intersecting the alternate columns in the other row.

FIG. 8 is a perspective view an application of the underground wall formed by the present invention in which the underground wall is employed as a boundary wall of a water reservoir, dam and the like structure which directly contacts the stored water in the facility;

FIG. 9 is a perspective view of a further application of the underground wall formed by the present invention in which the underground wall is constructed at the site of a reservoir; and

FIG. 10 is a schematic view of a still further application of the underground wall formed by the present invention in which the underground wall is employed as a reinforcing means for the foundation of a building and the like structure.

PREFERRED EMBODIMENTS OF THE INVENTION An apparatus for carrying out the method of the present invention is generally shown with reference numeral 2 which is disposed on the ground 1 with the earth and soil formation underneath which is to be solidified and densified and the apparatus generally comprises a hollow shaft 3 having integral cavity digging means at the lower end and integral openings or nozzle means in the peripheral wall through which an earth solidification and densification liquid agent is pumped into the earth and soil formation. The shaft 3 is connected through a pipe 4 to a pneumatic pump to be supplied with the earth solidification and densification liquid agent under pressure. The apparatus further comprises a drive mechanism 5 which operates in such a manner that the drilling means of the shaft can drill a cavity in the earth and soil formation as the shaft advances into the earth and soil formation to a predetermined depth as the shaft is rotated and when the cavity has been completed, the shaft is pulled upwardly as it is rotated and at the same time, the pump is actuated to pump the earth solidification and densification agent through the nozzle means radially into the earth and soil formation.

The cavity forming and liquid agent pumping operations are performed in such a timed relationship that after a cavity 6 has been drilled to a predetermined depth in the earth and soil formation, the drilling operation is stopped and at the same time the earth and soil solidification and densification liquid agent is pumped from the pump through the pipe 4 into the shaft 3 under a high pressure of up to 350 atmospheres of pressure.

The earth and soil solidification and densification liquid agent suitably employed in the method of the invention may be water glass principally comprising sodium silicate, polymer principally comprising acrylamide or other liquid pulp waste.

In cooperation, when the apparatus 2 positioned at a selected area on the ground the earth formation underneath which is to be solidified and densified is actuated, the drive mechanism 5 is actuated to drive the shaft 3. When driven, the hollow shaft 3, begins to vertically advance into the earth and soil formation while rotating to dig a cavity 6 with its digging means in the formation as shown in FIG. 1. When the tip or lower end of shaft 3 has reached a predetermined depth or has completely formed the cavity 6 as shown in FIG. 2, the advancement movement of the shaft 3 is stopped and the shaft is gradually retracted or pulled upwardly out of the cavity 6 while rotating. Simultaneously, the pneumatic pump is actuated to pump the earth solidification and densification liquid agent the pipe 4 into the shaft 3 under high pressure. The liquid agent is then pumped -mixing of the liquid agents with the adjacent earth and soil as shown in FIG. 4. In forming the column 7 in this way, the pumped liquid agent penetrates into the adjacent earth and soil formation section surrounding the shaft to mix therewith to solidify the earth and soil. FIG. 5 of the accompanying drawings shows a complete column has been completed, the apparatus 2 is moved to another area on the ground 1 adjacent to the previous area on the ground in the earth and soil formation underneath which the column has been already formed. The new ground area is so selected that a portion of the circle described by the column 7 is destroyed by the liquid agent pumped through the shaft nozzlemeans in the succeeding column forming operation in the earth and soil formation underneath the new ground area so that the adjacent columns can be connected to each other in the opposite peripheral sections. Thereafter, the above-mentioned procedure is repeated to form a second column in the vicinity of the first column. The same procedure is repeated until a desired underground wall comprising a predetermined number of columns is obtained.

Thus, it will be. understood that according to the present invention, by the use of the hollow shaft 3 which concurrently has both functions as cavity digging drill means and earth and soil solidification and densification liquid nozzlemeans, an underground wall comprising a plurality of columns can be effectively and simply formed without the necessity separate digging means which were otherwise necessary in the prior art underground wall forming methods.

FIG'. 6 shows an assembly of plural underground walls 11 each of which comprises a plurality of columns 7 formed by the'method of theinvention described hereinabove. As appreciated from the foregoing description, the wall assembly can be formed by successively moving the apparatus 2 from one place to another and repeating the above procedure each'time.

FIG. 7 shows two alternate applications of the underground wall formed by the method of the invention in one of which an assembly of plural underground walls 11 formed in accordance by the method referred to above is provided with a transverse through opening 14 in an intermediate height for receiving a piping 15. In the other application shown in FIG. 7A, a wall assembly comprising a plurality of inclined underground walls 1 in two rows with the alternate columns in one row intersecting the alternate columns in the other row at an area adjacent to and below the top end so as to provide a transverse opening between the two opposite rows for receiving a piping or conduit 16.

FIG. 8 shows another application of the underground wall formed by the method of the invention in which an assembly of plural underground walls 11 each comprising a plurality of columns 7 formed as described hereinabove is employed in a hilly or mountainous district 17 so that the wall assembly can be employed as the earth and soil formation protection or collapse prevention means. Alternatively, such a wall assembly may be also 6 employed as boundary wall for a water reservoir or dam.

FIG. 9 shows a further application of the .underground wall of the invention in which the underground wall is formed in conformity with the contour of the bank 19 of a reservoir 18 so that the underground wall can be employed as the surrounding wall of the reser- VOlI.

FIG. 10 shows a still further application of the underground wall formed by the method of the invention in which the underground wall is employed as reinforcing means for the foundation of a building and the like structure. As seen in this figure, a plurality of underground walls 11 are juxtaposed in spaced relationship in the earth and soil formation beneath the foundation of a building 20 to be constructed such as a warehouse and the like structure to solidifying the earth and soil formation under the building so that the building can be built in stabilization.

To explain the boring machine and nozzle means employed in carrying out the method of the invention briefly, the rotational shaft 3 is provided with drill bits 21 at the lower end of the shaft and a plurality of nozzles 22, 23, 24 and 25 in the periphery of the shaft. Grout or earth and soil solidification agent is pumped through the pipe 4 into the shaft 3 and then forced through the nozzles 22 to 25 radially into the earth and soil formation.

The operation of the method of the invention will be explained in greater detail as follows. The boring machine including theshaft and associated parts is installed in the site when the underground wall is to be formed. An earth and soil solidification agent is prepared prior to the operation of the boring machine. The boring machine is operated to drive the shaft into the earth and soil formation while allowing the shaft to rotate about its axis to a predetermined depth in the formation to form a cavity therein. At this point the downward movement of the shaft is stopped and the shaft is then withdrawn from the cavity as the shaft rotates. At the same time, the pumping of the earth and soil solidification agent is initiated so as to force the agent to flow through the nozzles radially into the cavity to enlarge the diameter of the cavity continuously throughout the entire length of the cavity and to solidify the formation around the cavity. When the shaft returns to its initial position or retreat position, a column is formed.

The procedure according to the invention willbe described while referring to the drawings. FlG. l shows a partially formed cavity. FIG. 2 shows a complete cavity having a predetermined depth. FIG. 3 shows the start of the formation of a column in the cavity with the pumping of the earth and soil solidification agent radially into the cavity. FIG. 4 shows a further progression of the column formation operation, and FIG. 5 shows shows a completed column formed by the method of the present invention. I

. FIG. 1 shows a stage after the start of the operation on the boring machine 2 which is installed at the site where a continuous underground wall is to be formed and comprises a motor 26 which is supplied with power from a power source (not shown) through a power supply (not shown) and mounted on a support frame 27 together with other mechanisms of the machine. The motor has an output shaft 28 which is connected to a speed change gear 29 which in turn transmits a drive force to differential 30 which in turn transmits power to the drive mechanism whose drive shaft drives the hollow shaft 3.

The end of the drive shaft of the drive mechanism opposite to the differential has a mechanism which drives the hollow shaft 3 downwardly and upwardly. Such shaft driving mechanism is not shown in the accompanying drawings because the mechanism does not constitute any part of the invention and is conventional. in order to drill a cavity in the earth and soil formation by the employment of the shaft 3, the shaft is driven into the formation to a predetermined depth as the shaft rotates. As the shaft is driven in the manner as mentioned above, the drill bits at the lower end of the shaft also rotate to dig the earth and soil out. After the cavity has been formed to a predetermined depth in the formation, the drive mechanism 5 is reversed in operation to withdraw the shaft from the cavity. Before the shaft is withdrawn, the movement of' the shaft is temporarily stopped. When the shaft 3 is stopped but before it is .withdrawn, the earth and soil solidification agent is pumped into the shaft and out through the nozzles. The agent is pumped under high pressure so as to enlarge the dimater of the cavity continuously throughout the length of the column formed. This means that the agent is pumped under pressure throughout-the length of the cavity. More particularly, as the shaft 3 is gradually withdrawn from the cavity while the grout or earth and soil solidification agent is forced out through the nozzles, a column having a diameter greater than the diameter of the cavity is continuously formed. When the procedure is repeated at successive adjacent areas of the first formed column, an underground wall comprising a plurality of continuous successive columns can be formed.

As clear from the foregoing, according to the present invention, an underground wall is simply formed by advancing the hollow shaft which concurrently functions as cavity drilling means and nozzle means into the earth and soil formation as the shaft is rotated to form a cavity having a predetermined depth and upon the completion of the cavity drilling operation, the shaft is retracted or pulled up out of the cavity as the shaft is rotated and simultaneously, the earth and soil solidification liquid agent is pumped through the openings or nozzles in the retracting and rotating shaft radially into the earth and soil formation to form a column around the shaft from the bottom to the top of the cavity. After one column has been completed, the apparatus including the shaft is moved to another place and the same procedure is repeated. In this way, a plurality of successive columns which constitutes a complete underground wall can be formed in a quite simple and highly efficient manner in a short period of time.

And since the earth and soil solidification and densification liquid agent is pumped into the earth and soil formation under high pressure, the liquid agent penetrate into the earth and soil to mix therewtih therewith to solidify the earth and soil formation. Thus, the method of the present invention does not require conventional separate or manual digging means and steel sheet piles and therefore, it will be understood that the present invention accelerates the underground formation efficiency and reduces manual efforts necessary for such work.

In the foregoing description has been made of various embodiments of the invention, but it will readily occur to those skilled in the art that these are illustrative in nature, but do not limit the scope of the invention in any way. The scope of the invention is only limited by the appended claims.

What is claimed is:

l. A method for the formation of an underground wall comprising a plurality of successive columns in the earth and soil formation comprising the steps of driving a vertically and rotationally movable hollow shaft having drill means at the lower end and nozzle means in the periphery wall thereof by means of a boring machine into said earth and soil formation in a first area as the shaft rotates to a predetermined depth in the formation to form a cavity therein, after said cavity of said predetermined depth has been formed, withdrawing said shaft from said cavity and simultaneously pumping an earth and soil solidification and densification agent under high pressure through said nozzle means radially from the shaft into said cavity continuously throughout the length of said cavity to destroy the formation area surrounding the cavity so as to form an earth and soil formation solidification column which has a diameter continuously larger than the cavity throughout the length of said cavity; moving said movable hollow shaft to successive areas adjacent to said previously formed column; and at each adjacent area driving said verti cally and rotationally movable hollow shaft having said drill means at the lower end and said nozzle means in the periphery wall thereof by means of said boring machine into said earth and soil formation as the shaft rotates to a predetermined depth in the formation to form an adjacent cavity therein, after said adjacent cavity of said predetermined depth has been formed, withdrawing said shaft from said adjacent cavity and simultaneously pumping an earth and soil solidification and densification agent under high pressure through said nozzle means radially from the shaft into said adjacent cavity continuously throughout the length of said cavity to destroy the formation area surrounding said adjacent cavity so as to form an earth and soil formation solidification column which has a diameter continuously larger than the cavity throughout the length of said adjacent cavity, said adjacent areas being selected such that a portion of the periphery of the previously formed column at the first area is destroyed by the liquid agent pumped in at said successive areas whereby the adjacent columns are continuously connected to each other throughout the length of said columns in the opposite peripheral sections of the adjacent columns.

2. The method as set forth in claim 1, in which said drill means are provided at the lower end of said shaft in parallel to the axis of the shaft and said nozzle means are provided in the peripheral wall of the shaft at right angles to the axis of the shaft.

3. The method of the formation of an underground wall in the earth and soil formation as set forth in claim 1, in which said earth and soil solidification and densification liquid agent is pumped under a high pressure up to 350 atmospheres of pressure. 

1. A method for the formation of an underground wall comprising a plurality of successive columns in the earth and soil formation comprising the steps of driving a vertically and rotationally movable hollow shaft having drill means at the lower end and nozzle means in the periphery wall thereof by means of a boring machine into said earth and soil formation in a first area as the shaft rotates to a predetermined depth in the formation to form a cavity therein, after said cavity of said predetermined depth has been formed, withdrawing said shaft from said cavity and simultaneously pumping an earth and soil solidification and densification agent under high pressure through said nozzle means radially from the shaft into said cavity continuously throughout the length of said cavity to destroy the formation area surrounding the cavity so as to form an earth and soil formation solidification column which has a diameter continuously larger than the cavity throughout the length of said cavity; moving said movable hollow shaft to successive areas adjacent to said previously formed column; and at each adjacent area driving said vertically and rotationally movable hollow shaft having said drill means at the lower end and said nozzle means in the periphery wall thereof by means of said boring machine into said earth and soil formation as the shaft rotates to a predetermined depth in the formation to form an adjacent cavity therein, after said adjacent cavity of said predetermined depth has been formed, withdrawing said shaft from said adjacent cavity and simultaneously pumping an earth and soil solidification and densification agent under high pressure through said nozzle means radially from the shaft into said adjacent cavity continuously throughout the length of said cavity to destroy the formation area surrounding said adjacent cavity so as to form an earth and soil formation solidification column which has a diameter continuously larger than the cavity throughout the length of said adjacent cavity, said adjacent areas being selected such that a portion of the periphery of the previously formed column at the first area is destroyed by the liquid agent pumped in at said successive areas whereby the adjacent columns are continuously connected to each other throughout the length of said columns in the opposite peripheral sections of the adjacent columns.
 2. The method as set forth in claim 1, in which said drill means are provided at the lower end of said shaft in parallel to the axis of the shaft and said nozzle means are provided in the peripheral wall of the shaft at right angles to the axis of the shaft.
 3. The method of the formation of an underground wall in the earth and soil formation as set forth in claim 1, in which said earth and soil solidification and deNsification liquid agent is pumped under a high pressure up to 350 atmospheres of pressure. 